RE: L2vpn Digest, Vol 95, Issue 58

Hi Sam,

If E-Tree service is provided in a scenario as Fig. 3 and Fig 4 in RFC 4762, then a CE (leaf or root) is connected to the MTU-s or PE-r, thus the AC should be terminated and the E-Tree service should be encapsulated by the MTU-s or PE-r. I don't quite understand why you need to "take VPWS PW as one AC", but even in that case, the attribute of the AC may be configured at the PE-rs. So what is the problem for H-VPLS?

Thanks
Yuanlong

Date: Sun, 22 Apr 2012 22:03:52 +0800
From: "Sam Cao" <yuqun.cao@...>
To: "'Jiangyuanlong'" <jiangyuanlong@...>
Cc: l2vpn@...
Subject: RE: The status of the approaches to the E-Tree solution?
Message-ID: <962A848896EF4678B17D76C826A7EAEF@v2comsam>
Content-Type: text/plain; charset="us-ascii"

Yuanlong,

I just collect all issues we discussed before, and we still can not make
agreement. I gave my comments on 2 items below. I will think other items
over and give my comments tomorrow.

2) HVPLS: If we follow Fig 3 or Fig 4 in RFC 4762 to deploy HVPLS,
PE-rs works in different manner, PE-rs should figure out AC type in VPWS
case, but can NOT configure it at all in Spoke PW case;
[JY] In the first place, why PE-rs need to figure out the AC type for a
spoke? The VLAN should be processed in the MTU, not in the PE-rs.
[Sam] Yuanlong, I understand your idea. It does NOT make sense for me.
First, Fig. 3 and Fig 4 in RFC 4762 are different cases. For VPWS (Fig. 3),
we can take VPWS PW as one AC. You know, PE-rs is termination of VPWS, so it
will add VLAN-ID to identify Root/Leaf. BTW, you will map several VLAN IDs
into one Root-VLAN ID or Leaf-VLAN ID on PE-rs, so we need to configure
Root/Leaf on PE-rs (Refer to your reply to Josh's comments).

4)  Encapsulation mode: If deploy HVPLS with Spoke PW mode, PE-rs
should work in tagged mode, otherwise PE-rs or egress PE will stripe S-VLAN
ID;
[JY] Is anything not working with tagged PW mode?
[Sam] Tagged mode works.

Regards,
 
Yuqun (Sam) Cao
E-mail: Yuqun.cao@...
 

-----Original Message-----
From: Jiangyuanlong [mailto:jiangyuanlong@...]
Sent: Sunday, April 22, 2012 5:43 PM
To: Sam Cao
Cc: l2vpn@...
Subject: RE: The status of the approaches to the E-Tree solution?

Hi Sam,

Please see my comments in line with [JY].

Regards,
Yuanlong


----------------------------------------------------------------------

Message: 1
Date: Sat, 21 Apr 2012 22:51:28 +0800
From: "Sam Cao" <yuqun.cao@...>
To: "'Lizhong Jin'" <lizho.jin@...>, "'Henderickx, Wim \(Wim\)'"
        <wim.henderickx@...>
Cc: l2vpn@...
Subject: RE: The status of the approaches to the E-Tree solution?
Message-ID: <1B88357C808B432E871CA9D678305B7C@v2comsam>
Content-Type: text/plain; charset="gb2312"

Hi all,

 

We reach an impasse:-).  BTW, Meeting minutes is ready now. We can get
E-tree summary from IETF site.

 

Today I collected all items we discussed before. They are,

 

1)       Silicon issue or chip limit;

2)       Network efficiency;

3)       Encapsulation mode, tag or raw;

4)       H-VPLS;

5)       Backwards compatibility, especially legacy PE or Non-supporting PE
with IEEE E-tree support joins E-Tree domain;

6)       Configuration change in operation, for example, Leaf-only ->
Root-Leaf-Mixed;

7)       S-VLAN preservation support;

8)       Multi-segment PW;

9)       VLAN ID allocation (Only for Dual-VLAN);

10)   Multi-AS deployment;

11)   ECMP;

12)   P2MP-PW;

13)   Ethernet OAM;

 

If we review the mail-list, CW approach has the following limits:

1)       Chip limit. Please read reply from Giles and Wim;

2)       Network efficiency: There are garbage fames which will be dropped
on egress PE since only egress PE can decide forward or drop frames while it
receives frames. Ingress PE can not decide forward or not. Yes, current
solution can support Hub-Spoke configuration, but as we know, the
configuration is not easy if the network is big. Dual-VLAN or Multi-PW
approach can break communication between Leaf-Only PEs via signaling.

3)       Backwards compatibility: Not all PEs supports control word. If one
can not support control word, it will not join E-Tree domain;

 

Dual VLAN has following limits:

1)       Chip limit: As we know, we need to push one VLAN into frames before
MPLS encapsulation on ingress PE and stripe it out on egress PE. This is
non-standard operation. Wait for confirmation from chip vendor;
[JY] Do you really consider tagged PW as non-standard?


2)       HVPLS: If we follow Fig 3 or Fig 4 in RFC 4762 to deploy HVPLS,
PE-rs works in different manner, PE-rs should figure out AC type in VPWS
case, but can NOT configure it at all in Spoke PW case;
[JY] In the first place, why PE-rs need to figure out the AC type for a
spoke? The VLAN should be processed in the MTU, not in the PE-rs.

3)       Multi-PW: Rafi figures this out, but we don?t think this over at
that time. I think that it also has same problem as H-VPLS has.
[JY] The same as above, only T-PE will deal with VLAN, S-PE only switches PW
label, so I can't see what is the problem.

4)       Encapsulation mode: If deploy HVPLS with Spoke PW mode, PE-rs
should work in tagged mode, otherwise PE-rs or egress PE will stripe S-VLAN
ID;
[JY] Is anything not working with tagged PW mode?

5)       Backward Compatibility: Just as Daniel mentioned, there is
compatibility issue if legacy PE joins E-Tree domain. For me, I don?t get
clear response from co-authors of Dual-VLAN.
[JY] Could you elaborate a little more what is the compatibility issue?
 

For all approaches, we don?t cover ECMP / Ethernet OAM till now.

 

Is there anything missed?

 

Regards,

 

Yuqun (Sam) Cao

E-mail: Yuqun.cao@...